Flotation process for nonsulphide ore



Patented Apr. 3, 1934 UNITED STATES 1,953,431 FLOTATION raoccss FORNONSULPHIDE can 7 John M. Patek, Milwaukee, Wis.

1% Drawing.

4 Claims.

This invention relates to the concentration of non-sulphide ore mineralsby flotation methods, especially in connection with the usual method ofusing a saponiflable substance as the principal 5 flotation agent, andis particularly adapted to the concentration of ores composed of oxides,silicates and other non-sulphide minerals, such as the oxide ores of tinand tungsten.

It is well known that the usual method of employing a fatty acid tocause the concentration by flotation of oxide, silicate andother'non-sulphide ore minerals is of little practical use since thegangue minerals are floated almost as readily as the ore minerals andlittle or no separation isaccomplished.

Special methods of flotation which improve the recovery of non-sulphideore from the gangueminerals have been proposed. At best, by these oldermethods, the concentrated ore contains 2 large quantities of gangueminerals which are not separable. For example, a natural material whichcontains the mineral oxide of a valuable element in small concentrationsmay at the same time contain large concentrations of quartz,

mica, tourmaline, epidote. The treatment of such a material by methodsknown prior to my invention results only in the separation of the quartzand mica leaving the concentrated material still contaminated with theepidote and tourmaline originally present. It is only under rare andpeculiar circumstances that such a separation is of practical value,to-wit: when the original material is luckily free of such constituentsas tourmaline, epidote, etc.

I have, on the other hand, discovered that many of the gangue mineralswhich formerly-were not" separable may now be separated by renderingthem unsusceptible to the collecting action of even the most activeflotation agents. This I 4 accomplish by contacting the mineral with ajellylike mixture formed by adding small amounts of a soluble silicateto a solution containing small amounts of certain compounds formed withthe specific metallic elements hereinafter to be speci- 4 fied. Thegangue mineral particle thus contacted will adsorb a coating ofmaterial, in the form of a metal silicate gel, formed by the interactionof the soluble silicate with the metal compound. This coating of metalsilicate gel provides a positive resistance to the collecting action ofthe notation agent and the particle s0 coated will not float. Theadsorption of the coating upon the gangue mineral particle depends uponthe chemical nature of the surface of the particle itself.

The structure of the gel substance formed is of Application September24, "1931,

Serial No. 564,974

the general form MO.SiO2(Hz0), wherein M represents the specific metalemployed. Thus the soluble silicate is used only to form an insolublemetal silicate gel which may be selectively adsorbed upon the surfacesof the silicate gangue minerals. A moderate excess of the gel in systemis unimportant for this reason. Likewise unimportant is the source ofthe gel. A soluble silicate may be first reduced to silicic acid byadding strong acid and a soluble metal compound solution, such as limewater added to form the gel, which may then be introduced to the flota-.tion machine. Many of the non-sulphide ore minerals bear a very weaksurface attraction in contrast to the strong surface atraction of thegangue silicates. The ore minerals, consequently, do not adsorb the gelsubstance, and are, therefore, easily floated by active flotationagents. I

The metal compounds added to the flotation circuit do not include allmetals, but only metals of a specific class. This class includes metalswhich have a certain definite characteristic in common, namely, theability to form a. soluble oxide or hydroxide in an alkaline solution.Metals which form such soluble oxides or hydroxides in an alkalinesolution will henceforth be referred to as soluble oxide forming metals.They are of two types:

1.Amphoteric metals 2.-Alkaline earth metals I Amphoteric metals may besharply difleren tiated from all other metals, because amphoteric metalsare the only metals that combine with oxygen to form chemical radicleswhich behave as anions. The'type of compound in which the amphotericmetals are introduced into the flotation circuit is the alkalinecompound of the metal oxide. An example is sodium aluminate.

The second type of soluble oxide forming 95 metals, the alkaline earthmetals, are used as oxides or hydroxides. The principal alkaline earthmetals are calcium, magnesium, strontium and barium. When compared tothe amphoteric metals, their cost is so low that they find applicationwhere a low cost flotation agent is essential.

' In my process the material to be treated is ground and mixed withwater to form a pulp in the usual manner. To the pulp is then added asmall amount of a compound containing a metal, let us say, of the typedefined above as the alkaline earth metal type. To the pulp is alsoadded an amount of soluble silicate slightly in excess of the addedcompound of the metal of the alka- 11o compounds are among thoseadvantageously incorporated in this manner.

As a specific example of one manner of carrying on my invention, I maytake 2000 grams of wolframite ore, which has been ground and mixed withwater to form a pulp. To the pulp I then add 3 grams of sodium aluminateand 5 grams of sodium silicate. The charge is then agitatedand' in thepresence of 1.5 grams of oleic acid and 0.2 grams of pine oil, subjectedto flotation in the usual manner. A more specific example is as follows:To 10 drops of sodium silicate in a test tube was added 2 0.0. of waterand 1.5 0.0. of dilute sulfuric acid, followed by 2 0.0. of saturatedcalcium hydroxide solution. A clear, firm gel formed in the tubeimmediately. The gel was then added to a 50 gram flotation machinecontaining a partially concentrated cassiterite ore containing 26.5%tin. To the mixture was added water and the ore pulp was then agitatedfor several minutes followed by the addition of 0.5 lbs. per ton ofoleic acid and 0.2 lbs. per ton of terpineol. Flotation was carried outin the usual manner and the. cassiterite recovered in the froth. Thetailings contained 1.5% tin and the concentrate contained 47% tin,showing a recovery of 98% ofthe tin. l

, While I have fully described above the process of my invention andhave given particular directions for, the practice thereof, I wish it tobe understood that I do not intend that the scope of the Letters Patentbe limited thereby, but only to be limited by the range of the inventionas set forth in the appended claims.

I c1aimas my invention:

1. The process of concentrating non-sulphide ores which consists ingrinding the ore, mixing the same with water to form a pulp, adding theoxide of an alkaline earth metal, a soluble silicate and a saponifiablesubstance, agitating the mixture while supplying air thereto, andremoving the froth produced thereby.

,2. The process of concentrating non-sulphide ores which consists ingrinding the ore, mixing the same with water to form a pulp, adding analkaline earth metal silicate gel, a saponifying substance and afrothing agent, agitating the mixture while supplying air thereto, andremoving the froth produced thereby.

3. The process of concentrating non-sulphide ores which consists ingrinding the ore, mixing the same with water to form a pulp, addingcalcium hydroxide, a soluble silicate and a saponify-, ing substance,agitating the mixture while supplying air thereto, and removing thefroth produced thereby. a

4. The process of concentrating non-sulphide ores which consists in,grinding the ore, mixing the same with water to form a pulp, adding analkaline earth metal oxide and soluble silicate, so as to form agel,.and a saponifiable substance, agitating the mixture while supplyingair thereno to to form a froth, and removing the froth produced thereby.

JOHN M. PATEK.

